DNA replication in Drosophila melanogaster embryos; We have undertaken an analysis of DNA replication in D. melanogaster embryos, as a model system for the study of eukaryotic DNA replication. Our current efforts are aimed at elucidating the structure and synthetic capacity of the DNA polymerase alpha which we have purified to homogeneity from these embryos. Role of the recA protein in homologous recombination in E. coli; We have purified the product of the recA gene of E. coli to homogeneity and discovered that it catalyzes the assimilation of a single-stranded DNA segment into an homologous region of a duplex DNA molecule in a reaction which is coupled to the hydrolysis of ATP to ADP and P. We are presently attempting to acquire a detailed understanding of this complex reaction, which is a crucial step in homologous recombination in E. coli.